Honing is a process to finish an object, such as a hole, to a final size, after an imprecise operation such as drilling, and to produce a fine surface finish. Honing is usually on the inner-diameter, but can also be done on the outer-diameter of an object. Grinding is common on outer-diameters, but can be very expensive. Abrasive stones are often used for both inner and outer-diameter honing but are expensive, fragile and come in limited number of grit sizes and lengths. Honing is generally not a selective process—the honed area depends on the length of the stones, and very short stones may not produce a hone finish that is accurate. One example of an inner-diameter hone is U.S. Pat. No. 6,558,240 which is only suitable for inner diameter honing in a narrow range of hone grit sizes. The Sunnen Corporations FB-E external honing body is an outer-diameter honing tool using honing stones, but the tool is for use with a honing machine and only with fine grit honing stones. U.S. Pat. No. 6,669,531 claims honing on multiple surfaces; U.S. Pat. No. 6,074,282 and others claim outer-diameter honing but not on selected areas.
This Invention is directed to the task of honing the outer-diameter of pipe or precision cylindrical tubing, to remove ovality and reduce the outer-diameter to some finished size. Further, it is desired to only work certain sections of the length of the tubing so as to not waste labor and tool life.
Honing tools with abrasive stones are generally limited to removal of very small amounts of material. In this Invention, both small and large amounts of removal are anticipated, upwards of 0.25 mm (0.01″) for which sand paper or the like are more appropriate and less expensive. Sanding belts are available in wider grit ranges than honing stones for a wider rate of material removal. Since selective honing is desired, the Invention incorporates sanding belts into an abrading mechanism, where the belt width represents the honed area length. At least two assemblies are preferred to hold the work-piece concentric with the tool body, ensuring the honed areas are concentric. More than two assemblies can be included.